Restrainers for rapid access, air stable, regenerable, metal chelate developer solutions

ABSTRACT

Fog is suppressed in development with rapid access, air stable, regenerable metal chelate developer solutions by the inclusion therein of a fog restrainer selected from 2mercaptobenzothiazole, L-thiazolidine-4-carboxylic acid, and Nmethylbenzothiazole-p-toluene sulphonate.

United States Patent 1191 Newman et al.

[ June 3, 1975 1 RESTRAINERS FOR RAPID ACCESS, AIR STABLE, REGENERABLE, METAL CHELATE DEVELOPER SOLUTIONS [75] Inventors: Norman Newman; Richard S. Fisch,

both of St. Paul, Minn.

[73] Assignee: Minnesota Mining and Manufacturing Company, St. Paul, Minn.

22 Filed: Aug. 24, 1973 21 Appl. No.: 391,510

UNITED STATES PATENTS 3,017,270 1/1962 Tregillus 96/29 3,567,441 3/1971 Vogt 96/66 R 3,723,126 3/1973 Price 96/61 M 3,748,138

7/1973 Bissonette 96/66 R Primary Examiner-Mary F. Kelley Attorney, Agent, or Firm-Alexander, Sell, Steldt & DeLaHunt [5 7] ABSTRACT Fog is suppressed in development with rapid access, air stable, regenerable metal chelate developer solutions by the inclusion therein of a fog restrainer selected from Z-mercaptobenzothiazole, L-thiazolidine- 4-carboxylic acid, and N-methylbenzothiazole-p toluene sulphonate.

14 Claims, No Drawings RESTRAINERS FOR RAPID ACCESS, AIR STABLE, REGENERABLE, METAL CHELATE DEVELOPER SOLUTIONS In photographic processes where a silver image is produced by reduction of silver halide salts (development), some spurious non-image silver is also produced. Such spurious non-image silver is generally called fog. Various materials known as restrainers, have been added to development baths to limit the production of fog. The most common of these restrainers contain an active halide to restrain the formation of fog. One significant problem exists with the use of such restrainers in developer baths. The development restraint caused by these materials is active over all the silver produced, and some amount of image silver as well as spurious non-image silver is withheld from development. Organic materials known as anti-foggants le.g. imidazole) have also been used in conventional developing processes, either alone or in conjunction with halide, to insure that more fog than image density is removed.

In US. applications Ser. Nos. 391,508, 391,507, and 391,506, filed concurrently with this application, rapid access, air stable, regenerable metal chelate developer solutions are disclosed. Most materials used as fog suppressants in conventional developer solutions have been found to suppress fog only while reducing the silver image density more than the fog density. In developing processes using rapid access, air stable, regenerable metal chelate developers, only three compounds have been found, in conjunction with halide (1, Cl, and especially Br), which reduce the densities of fog to a greater extent than the density of the visual image is reduced. These three compounds are 2-mercaptobenzothiazole, L-thiazolidine-4-carboxylic acid and N-methylbenzothiazolium p-toluenesulphonate.

The term metal chelate developing agent as used in the practice of this invention refers to those materials which consist of a metal with a variable valency (e.g., iron, lead, vanadium, chromium, titanium, etc.) associated with a chelating agent, sequestering agent or complexing agent (these terms are alternative herein). The metal portion of the metal chelate is required to have at least two distinct valence states (e.g., Fe and Fe for iron).

The lower valent iron is the developing agent (reducing agent) which usually functions by simple electron transfer to the silver ion; the higher valent metal ion is formed as a result. The presence of these latter oxidized ions (higher valent ions) provides an antagonistic effect toward the further reduction of silver halide by the lower valent ion, and small buildup of such higher valent ions by either the result of development or aerial oxidation is sufficient to seriously hamper the development reaction.

The chelate portion of the metal chelate are those chelate, sequestering or complexing materials whose stability constant for the higher valence state of a metal is higher than that for the valence state. These stability constants may be found for example in reference bookds (e.g., Stability Constants of Metal-Ion Complexes, Chemical Society, London, 1964). In the most preferred embodiments, the ratio of the stability constants of the higher state to the lower state should be at least 100:1 respectively. The most preferred chelating agents in the practice of this invention are ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid (EDTA and DTPA respectively).

For a particular metal ion developer, satisfactory complexing agents are those which form a more stable complex with the higher valent ion than the lower valent ion (Mason, Photographic Chemistry, Focal Press, 1966, p. 173) thus reducing the concentration of the antagonist higher valent ion. The fact is, nevertheless, that the buildup of the higher valent ion, either by the development reaction or aerial oxidation, proceeds and even in the presence of these complexing agents, the baths eventually deteriorate and become unuseable (C. E. Mees, 2nd Ed., McMillan, 1942, p. 332). The addition of various additives such as formaldehyde (Brit. Pat. Specification No. 741) 1889, though successful in hardening the emulsion, gave no improvement in aerial stability.

Rzymkowski in 1941 [Rzymkowski, Wiss. Photo. 40 136 (1941)] categorized the metal complex developers as having the following structure:

in which Alk is an alkali metal, M is the metal ion of a multiple valent metal and R is an organic radical and y mz n. These materials are included within the present disclosure of metal chelates.

The earliest successful use of iron, i.e., ferrous ion, in a developer was by Carey Lea [B. J. Phot. 24, 292 (1877)]. Lea utilized a complexing agent, potassium oxalate, in his developer.

In 1951 Rausch and Russel introduced developers using a different class of complexing agents which showed much greater superiority in their affinity to complex the higher valent metal species and so exhibited some improved performance of the developers. These materials were aliphatic amino-polycarboxylic acids and their water soluble salts (Br. Pat. Specification No. 720,235) commonly known at the times as chelating or sequestering agents which gave rise to the term metal chelate developers. Rzymkowski in 1951 (Pharmazie (1951) 6, p. -6) noted that these developers fitted in his definition and equated the terminology of metal complex and metal chelate developers [lndustrie Chim. Belg. Spec. No. 645-6 (1955)]. This terminology based in this narrowed definition for the word complex persists to the present and in fact there are few metal complex developers which are based on a complexing agent not a chelating agent of one sort or another.

The practice of this invention generally relates to air stable, rapid access, regenerable metal chelate developer solutions. The terminology air stable, rapid access and regenerable describe substantive properties of the developer solutions.

Air stable metal chelate developer solutions are those which do not undergo a change of greater than 50 millivolts in its redox potential during 2 days exposure to air (cf. US. application Ser. No. 391,505, filed concur rently with this application). In the use of these metal chelate developers, such air stability enables the maintenance of a desired level of developmental activity without requiring the gross addition of replacement chemistry.

The solutions of this developing system must also be rapid access developers. This means that the dwell time in the developer need only be 4 minutes or less for producing a useful image having 90% of the useful Dmax produced by that developer in 8 minutes with the same exposure and handling of the photographic element. The useful Dmax may, of course, depend upon the particular application of the photographic element, but must be viewable over fog levels of the elements. It is preferred that the dwell time need be only 2 minutes for 90% of the useful Dmax of 4 minutes dwell time in the same developer.

wherein X is an oxygen atom or imino group, R is any group which does not render the ascorbic acids water insoluble and is a non-interfering group. Noninterference means that the R group does not cause stearic hindrance, is not chemically reactive with other portions of the molecule, is not a coordinating group for the molecule and is not more electopositive than a saturated hydrocarbon residue. Peferably R is an aryl group or a group of the formula The solutions must also be regenerable. This means 10 that the solution, afer or during use may be maintained 1 at the same level of electrochemical potential without R CH2(CHOH)"-1 the gross addition of replacement chemistry. The solutions of this invention may be maintained at the proper wherein n is a positive integer from 1 to 4 and R is eilevel of chemical activity by the recution of the spent ther a hydrogen atom or hydroxyl group when n is 2 to (oxidized) metal ions to their development (reduced) 4 and is an hydroxyl group when n is 1. st i hout he dition of ppl m n l h mistry, Of these materials ascorbic acid and isoascorbic acid but y y the fiohtachhg Spent Theta] ion with are the most preferred materials. R may be any nona metal which will reduce the ion. ln add1t1on,the term i t f i organic group which does not render the f g f means 'f 1f thh System allowed to Stahd ascorbic acid type material water insoluble, as R is not In hot p h r the operahhg elechohlohve the developmentally active portion of the compound. potential of the solution can be reached w1th1n one The f ll i examples ill id i a f h d hour by contacting the solution with sufficient surface standing f the prgseht invention area of reducing metal (cf. U.S. Ser. No. 391,505, filed concurrently with this application).

The three copending metal chelate developer appli- EXAMPLE I cations disclose three different classes of rapid access, Samples of a controlled Sensitometricahy exposed Stable, l'egeherablei deYeIOPeT solutlonsh' commercial high contrast (microfilm type) chlorobro- Catloh 391,508 dlcloses two Component i mide silver halide element were developed in various access Stable regfmerablei loywmrast metal developer solutions specified below. The samples were late developer solutions comprising at least 0.05M developed for 30 Seconds at F. washed, fixed, metal chelate developer and at least 005M 9 the washed, and dried. Resultant densities were measured devekfper Pomponent slected from amldohgalhc with a MACBETH densitometer at identical exposure acid, tannlc acid, and 2,5,d1-tert-butyl hydroqumone. values g i r l tgi l e re gi r'le jsglg fiiggio rfgg fj g f gg: A standard metal chelate developer solution accordv i mg to the practice of U.S. Ser. No. 391,507, was made nent metal chelate developer solutions comprising at u accordin to th f H f l I least 0.05M ofat least one metal chelate developer and g e o Owmg Ormu anon 0.05M of a compound selected from ascorbic acid, sugar-type derivatives of ascorbic acid and the stereoi- 40 I n m somers and diastereoisomers of ascorbic acid and its sugar-type derivatives. U.S. application Ser. No. Fe SO .14 M 391,507 discloses a ternary rapid access, air stable re- M generable metal chelate developer solution comprising [Sig-ascorbic acid M at least 0.05M metal chelate developer, at least 0.05M Phenidone M of the ascorbic acid materials (same as listed for Ser. S g 2 n No. 391,506, and 0.1mM of a third developer material pH 8.25 8.50 8.10 I (which is present in amount less than that of the ascorbic acid developer). The third developer material is selected from phenidone, hydroxylamine sulfate, glycin, Additive solutions of various restraining agents were cysteine hydrochloride, and 4-amino-N-ethyl-N-(B- made up, and sufficient solution added to the standard methanesulfoneamidoethyl)-m-toludine. These three formulation to produce a 0.10 g/liter concentration of applications are incorporated herein, in their entirety the additive in the developer formulation. for their disclosure of rapid access, air stable, regenerable metal chelate developer solutions. The restrainers TABLE of this invention will work satisfactorily in air stable, rapid access, regenerable metal chelate developer solu- Material Form. tions and particularly well with the developer solutions latinn ens ties et of those three: ppl h Without With The ascorbic acids, including the sugar-type deriva- Addmve Addmve tives of ascorbic acid as well as ascorbic acid, may be Fog image Fog image represented by the generic structural formula:

.IOdOZiCCUC- l .25 1.65 .19 1.40 0. 19 OH OH Acid I I R CH c c C X 2-Methyl 1 26 1.64 .23 1.48 0.11

lmidazole i 0 i lmidazole l .28 1.64 .22 1.46 0. 19

TABLE lContinued Material Formulation Densities (A) ANet Without With Additive Additive Fog lmage Fog lmage 2-Mercapl .25 1.69 .14 1.68 +0.10 tobenzothiazole 5-Mercapto-3- l .25 1.63 .15 1.43 (l. phenyl-l,3,4- thiadiazol-Z- thione 2- l .26 1.65 .17 0.98 -0.58 Benzimidazolethiole l .25 1.65 .20 1.64 .04 -thiazolidine- 4-carboxy1ic acid 4-Phenyl-5- l .29 1.63 .27 1.23 .38 mercaptotetrazole 2- l 28 1.63 .19 1.44 .10 Benzothiazolyl Hydrazine 2-Benzothia l .24 1.68 .25 1.49 .20 1,3-diazole l-Phenyl-Z- l 28 1.65 28 1.33 32 tetruzolium-S- thione N-Methylbenll .36 1.93 .22 1.86 .07 zothiazolium p-toluenesuh fonate Benzotriazole ll .38 1.94 .22 1.43 .35

2-Mercaptoll .35 1.89 .28 1.07 .75 thiazoline 2-Mercapto-l- 111 .25 1.48 .12 .78 .57

methylimidazole 2- 111 .22 1.52 .14 .91 .53 Thiobarbituric Acid The net change was determined by substracting the total change in image density from the total change in fog density. The positive numbers indicate a greater absolute decrease in fog density then absolute decrease in image density.

As can be seen, in rapid access, air stable, regernable metal chelate developer solutions, only three compounds have been found which. in conjunction with halide, are able to reduce fog without an equal or greater reduction in image density.

As noted above, the restrainers of this invention must be used in conjunction with halide in the developer bath. The halide should be present in quantities of from 0.05 mM to 0.3 M and the organic restraining agent should be present in concentrations from 0.03 mM to 50 mM or its solubility limit.

EXAMPLE II The high contrast elements of Example 1 were exposed and developed in the following developer solution as in Example 1 except that development time was 45 seconds.

A standard metal chelate developer solution was made according to the following formulation:

TiCl 0.08 M Diethylenetriamine- 0.16 M

pentaacetic acid Ascorbic Acid 0.15 M

Na SQ- 0.06 M

KBr 0.6 mM

Additive solutions of various restraining agents were made up, and sufficient solution added to the standard solution to produce a 0.10 g/liter concentration of the restrainer in the developer solution. The sensitometric data appear below:

The data show the greater reduction in fog density than image density with the practice of this invention.

What we claim is:

1. A rapid access, air-stable, regenerable metal chelate developer solution, the metal chelate selected from the group consisting of iron, titanium, and vanadium chelate developers, including therein as fog restrainer halide and a compound selected from the group consit ing of Z-mercaptobenzothiazole L-thiaZolidine-4 carboxylic acid, and N-methylbenzothiazolium ptoluene sulphonate.

2. The developer solution of claim 1 wherein the metal chelate developer solution comprises an aqueous solution of a metal chelate developer and at least one developer selected from gallic acid, tannic acid, amidol and 2,5-ditert-butyl hydroquinone.

3. The developer solution of claim 1 wherein the metal chelate developer solution comprises an aqueous ternary system of at least one metal chelate developer, a second developer selected from ascorbic acid, sugartype derivatives of ascorbic acid, stereoisomers and diastereoisomers of ascorbic acid and its sugar-type derivatives, and a third component selected from l-phenyl-3-pyrazolidone, glycin, cysteine, hydrochloride, hydroxylamine monosulfate and 4-aminO-N-ethyLN-(B- methanesulfoneamidoethyl)-m-toluidene.

4. The developer solution of claim 1 wherin the metal chelate developer solution is an aqueous high contrast developer solution comprising a metal chelate developer and a second developer selected from ascorbic acid, sugar-type derivatives of ascorbic acid, stereoisomers and disastereosiomers of ascorbic acid and sugar-type derivatives of ascorbic acid.

5. The solution of claim 1 wherein the halide is present in a concentration of from 0.05 mM to 0.3 M and the compound is present in a concentration of at least 0.03 mM.

6. The solution of claim 1 wherein the metal of the metal chelate developer is selected from iron and titanium.

7. The developer solution of claim 1 wherein the chelate portion of the metal chelate has a ratio of the stability constant for the higher valence state of the metal of the metal chelate developer to the stability constanat for the lower valence state of said metal which is at least 100:1.

8. The developer solution of claim 1 wherein the chelate portion of the metal chelate is selected from ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid.

9. The developer solution of claim 3 wherein the second developer is a water soluble compound represented by the formula:

R-CH-C=C-cwherein X is an oxygen atom or imino group, and

R is a non-interfering group.

10. The developer solution of claim 4 wherein the second developer is a water soluble compound represented by the formula:

OH OH c-c=x R H C wherein X is an oxygen atom or imino group, and

R is a non-interfering group.

1 1. The developer solution of claim 9 wherein R is an aryl group or a group of the formula:

wherein n is a positive integer from 1 to 4 and R is either a hydrogen atom or hydroxyl group when n is 2 to 4 and is a hydroxyl group when n is l.

13. The developer solution of claim 11 wherein the chelate portion of the metal chelate has a ratio of the stability constant for the higher valence state of the metal of the metal chelate developer to the stability constant for the lower valence state of said metal which is at least :1.

14. The developer solution of claim 12 wherein the chelate portion of the metal chelate has a ratio of the stability constant for the higher valence state of the metal of the metal chelate developer to the stability constant for the lower valence state of mind of said metal which is at least 100:1.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3, 887,375 DATED June 3, 1975 INVENTOR(S) 1 Norman Newman and Richard S. Fisch It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below;

C01. 1, line 7, "iron" should be -ion-.

Col. 3, line 47, after "and 0.1mM" should be added to lOOmM--.

Col. 5, line 19, "-thiazolidine-" should be -L-thiazolidine Col. 6, line 66, "disastereosiomers" should be -disastereoisomers-.

Col. 7, line 11, "constanat" should be constant-.

Col. 8, line 17, "any-aryl" should be -an aryl--.

Col. 8, line 33, "valence state of mind of said metal" should be --valence state of said metal-.

Signed and Scaled this fourteenth D 3) Of October 19 75 [SEAL] Arrest.-

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner oflatents and Trademarks 

1. A rapid access, air-stable, regenerable metal chelate developer solution, the metal chelate selected from the group consisting of iron, titanium, and vanadium chelate developers, including therein as fog restrainer halide and a compound selected from the group consiting of 2-mercaptobenzothiazole L-thiazolidine-4-carboxylic acid, and N-methylbenzothiazolium p-toluene sulphonate.
 1. A RAPID ACCESS, AIR-STABLE, REGENERABLE METAL CHELATE DEVELO CONSISTING OF IRON, TITANIUM, AND VANADIUM CHELATE DEVELOPERS, INCLUDING THEREIN AS FOG RESTRAINER HALIDE AND A COMPOUND SELECTED FROM THE GROUP CONSISTING OF 2-MERCAPTOBENZOTHIAZOLE L-THIAZOLIDINE-4-CARBOXYLIC ACID, AND NMETHYLBENZOTHIAZOLIUM P-TOLUENE SULPHONATE.
 2. THE DEVELOPER SOLUTION OF CLAIM 1 WHEREIN THE METAL CHELATE DEVELOPER SOLUTION COMPRISES AN AQUEOUS SOLUTION OF A METAL CHELATE DEVELOPER AND AT LEAST ONE DEVELOPER SELECTED FROM GALLIC ACID, TANNIC ACID, AMIDOL AND 2,5-DI-TERT-BUTYL HYDROQUINONE.
 2. The developer solution of claim 1 wherein the metal chelate developer solution comprises an aqueous solution of a metal chelate developer and at least one developer selected from gallic acid, tannic acid, amidol and 2,5-di-tert-butyl hydroquinone.
 3. The developer solution of claim 1 wherein the metal chelate developer solution comprises an aqueous ternary system of at least one metal chelate developer, a second developer selected from ascorbic acid, sugar-type derivatives of ascorbic acid, stereoisomers and diastereoisomers of ascorbic acid and its sugar-type derivatives, and a third component selected from 1-phenyl-3-pyrazolidone, glycin, cysteine, hydrochloride, hydroxylamine monosulfate and 4-amino-N-ethyl-N-( Beta -methanesulfoneamidoethyl)-m-toluidene.
 4. The developer solution of claim 1 wherin the metal chelate developer solution is an aqueous high contrast developer solution comprising a metal chelate developer and a second developer selected from ascorbic acid, sugar-type derivatives of ascorbic acid, stereoisomers and disastereosiomers of ascorbic acid and sugar-type derivatives of ascorbic acid.
 5. The solution of claim 1 wherein the halide is present in a concentration of from 0.05 mM to 0.3 M and the compound is present in a concentration of at least 0.03 mM.
 6. The solution of claim 1 wherein the metal of the metal chelate developer is selected from iron and titanium.
 7. The developer solution of claim 1 wherein the chelate portion of the metal chelate has a ratio of the stability constant for the higher valence state of the metal of the metal chelate developer to the stability constanat for the lower valence state of said metal which is at least 100:1.
 8. The developer solution of claim 1 wherein the chelate portion of the metal chelate is selected from ethylenediaminetetraacetic acid and diethylene-triaminepentaacetic acid.
 9. The developer solution of claim 3 wherein the second developer is a water soluble compound represented by the formula:
 10. The developer solution of claim 4 wherein the second developer is a water soluble compound represented by the formula:
 11. The developer solution of claim 9 wherein R is an aryl group or a group of the formula: R1CH2(CHOH)n-1-wherein n is a positive integer from 1 to 4 and R1 is either a hydrogen atom or hydroxyl group when n is 2 to 4 and is a hydroxyl group when n is
 1. 12. The developer solution of claim 10 wherein R is any aryl group or a group of the formula: R1CH2(CHOH)n-1-wherein n is a positive integer from 1 to 4 and R1 is either a hydrogen atom or hydroxyl group when n is 2 to 4 and is a hydroxyl group when n is
 1. 13. The developer solution of claim 11 wherein the chelate portion of the metal chelate has a ratio of the stability constant for the higher valence state of the metal of the metal chelate developer to the stability constant for the lower valence state of said metal which is at least 100:1. 